The present invention relates to a display device formed of an RGBW display panel module where an increase in brightness and a reduction in power consumption can be achieved, and which is improved upon with regards to a darkness in single colors, and in particular to a liquid crystal display device having a backlight.
The demand for middle- and small-sized displays having ultrahigh resolution, such as UMPC's, has tended to increase in recent years, and a reduction in the power in the system has become a significant issue. In this situation, RGBW pixel panels where white (W) sub-pixels (hereinafter referred to as W pixels) are added to conventional sub-pixels of red (R), green (G) and blue (B) (hereinafter referred to as RGB pixels) make it possible for the brightness to be increased, and therefore makes it possible to achieve a reduction in the power by reducing the scale of backlight, and thus it is considered that demand will increase in the future. Here, an RGB pixel means one color pixel formed of an R sub-pixel, a G sub-pixel and a B sub-pixel, and an RGBW pixel means one color pixel formed of an R sub-pixel, a G sub-pixel, a B sub-pixel and a W sub-pixel. One pixel is formed of a number of sub-pixels.
In RGBW pixel panels, though it is possible to increase the brightness by using W pixels, the brightness is low in the case where a single color is displayed without using W pixels. As a result, the brightness of a single color relative to white is low in the case where white and a single color are displayed, and thus a single color provides a dark image, and this is a factor in the deterioration of the image quality. Patent Document 1 (U.S. Pat. No. 7,221,381) can be cited as an example which discloses this type of prior art.